1. Field of the Invention
The field of the present invention is semiconductor packaging.
2. Description of the Related Art
Semiconductor packages commonly include a metal leadframe, which serves a base for the semiconductor package. Typically, the leadframe includes a central die pad, and a plurality of leads surrounding the die pad. One semiconductor die, or a plurality of stacked semiconductor dies, are coupled to the leadframe. Bond wires electrically couple bond pads of the semiconductor die(s) to the leads. A body of a plastic encapsulant encases the semiconductor die(s), an inner subportion of the length of the leads, and the bond wires. An outer subportion of the length of the leads extends from the encapsulant, allowing the leads to be electrically coupled to an external printed circuit board. Typically, leadframes are formed by mechanically stamping or chemically etching a continuous metal strip, which is made of copper (Cu), iron (Fe) or copper alloy (Cu Alloy), or its equivalent.
Packages including a stack of semiconductor dies are becoming popular, because more functions may be incorporated into a single package, without increasing the amount of space needed for mounting the package on the external printed circuit board. One difficulty associated with such packages is that, when stacking the semiconductor dies one on top of the other, adhesive used to couple the semiconductor dies together can contaminate the bond pads of the bottom semiconductor die. An alternative process wherein the two semiconductor dies are stacked on opposite sides of the die pad, i.e., with the die pad between them, avoids the contamination problem, but makes it difficult to handle the leadframe during manufacturing.